GEOS 3.9 + nowagyu = failure(4348Clip)

[pramsey]

The regression test 4348Clip in mvt.sql fails when run with --nowagyu against GEOS 3.9. The test expects an error between 21950 and 22050, but the area returned is

 ?column?  | st_area  
-----------+----------
 #4348Clip | 110888.5

It looks like the makevalid in 3.9 is coming up with a different answer than in 3.8 which is unfortunate to say the least. It's possible that the latest version of GEOS 3.9, which includes a change to buffer(0) would allow a zero-radius buffer to do a "better" valid formation than makevalid.

[pramsey]

Just for the backlink, this is coming out of upgrading the CI suite to 3.9 and in the --nowagyu build configuration, hitting tests from #4348.

[mdavis]

It is definitely worth trying out buffer(0) as a way of fixing invalidity caused by precision reduction. For that use case the behaviour of buffer(0) in dropping small loops should be totally acceptable. And it might be faster.

[Algunenano]

This is ticketed under GEOS ​https://trac.osgeo.org/geos/ticket/1038. The area returned by GEOS 3.9 is not the expected one. It was supposed to be fixed (and I remember passing the tests with 3.9 locally) so I don't know what happened.

To be honest, at this point I would rather drop non-wagyu builds rather than keep fighting GEOS.

[pramsey]

Drop non-wagyu builds. It's not like it's an option we encourage and we've vendored wagyu so there's no practical reason to maintain it that I can see.

[Raúl Marín <git@…>]

In a7a4c9e/git:

Fix NEWS typo and add reference to ticket

Closes #4824